Method of molten metal height control in curved mold continuous casting

ABSTRACT

WHERE R is the radius of curvature of the mold; K is the coefficient of crystallization of the molten metal; and V is the casting speed.   Continuous casting with a curved mold mounted so that when casting metal the meniscus thereof is above the horizontal plane passing through the center of curvature of the mold by a height H as determined by the relationship

United States Patent Inventors Appl. No. Filed Patented Viktor Nikolaevich Khorev ul. Bazhova, 130, kv. 107;

Georgy Lukich Khimich, ul. Lenina, 53, kv. 92; Vitaly Maximovich Niskovskikh, ul. Festivalnaya 21, kv. 60, all 01 Sverdlovsk, U.S.S.R.

Jan. 8, 1970 Nov. 30, 197 1 Original application Mar. 1, 1967, Ser. No. 619,622, now abandoned. Divided and this application Jan. 8, 1970, Ser. No. 1,527

METHOD OF MOLTEN METAL HEIGHT CONTROL IN CURVED MOLD CONTINUOUS CASTING 2 Claims, 2 Drawing Figs.

US. Cl 164/82, 164/273 Int. Cl B22d 11/10 Field of Search 164/82, 83, 89, 273, 274, 282, 283

[56] References Cited UNITED STATES PATENTS 2,947,075 8/1960 Schneckenburger et al. 164/282 X 3,313,006 4/1967 Barbe et al 164/283 3,367,399 2/1968 Easton 164/282 3,483,915 12/ l 969 Schneckenburger et al. 164/82 X FOREIGN PATENTS 706,309 3/1965 Canada 164/282 Primary Examiner-R. Spencer Annear Attorney-Holman & Stern ABSTRACT: Continuous casting with a curved mold mounted so that when casting metal the meniscus thereof is above the horizontal plane passing through the center ofcurvature of the mold by a height H as determined by the relationship where R is the radius ofcurvature ofthe mold;

K is the coefficient of crystallization of the molten metal; and V is the casting speed.

PAIENTEnnnvsomn 3.523.533

SHEET 1 OF 2 VIII/J71 PATENTEDHUV 30 mn SHEET 2 []F 2 METHOD OF MOLTEN METAL HEIGHT CONTROL IN CURVED MOLD CONTINUOUS CASTING This a division of our application Ser. No. 619,622 filed Mar. 1, 1967, now abandoned.

The present invention relates to a method casting metal in curved molds.

At the present time, plants are known in which the mold is disposed in such a manner that the meniscus of the molten metal during its casting is below the horizontal plane passing through the center of curvature of the mold (see the Pat. specification of the Federal Republic of Germany, No. 1,025,578,Aug. 1958.)

In the curved molds of said plants the solid skin of an ingot being cast is curvilinear; as a result, the floating nonmetallic inclusions and gas bubbles are thrust against and entrapped in the skin as it forms on the surface at the mold wall, said surface being generated at a small radius. This fact considerably impairs the quality of the ingot being cast.

An object of the present invention is to provide a method whereby the conditions of removal of nonmetallic inclusions and gas bubbles from the upper portion of a solidifying ingot are improved when continuously casting in a curved mold;

This and other objects are achieved due to the fact that in a continuous casting plant provided with a curved mold, the mold is mounted in such a manner and the pouring is regulated so that the meniscus thereof is above the horizontal plane passing through the center of curvature of the mold at a distance which is defined by the following equation:

3 4K2 H R sine V R is the radius of curvature of the mold;

K is the coefficient of crystallization; and

V is the speed of casting.

The nature of the present invention will further be made more fully apparent from a consideration of the following description of an exemplary embodiment thereof, taken in conjunction with the accompanying drawings, in which:

HO. 1 is a schematic diagram of a plant for continuous casting of metal; and

FIG. 2 is a nomograph to be used for determining the distance from the meniscus to the horizontal plane passing through the center of curvature of the mold depending upon the radius of curvature of the mold, casting speed and coefficient of crystallization.

The continuous casting plant comprises a curved mold 1 complete with copper plates 2, and a system of secondary cooling, composed of a zone 3 of walking bars and a roller zone 4. An ingot 5, to be cast in these plants, has the solid skin 6 and a molten core 7 with the meniscus 8.

The curved mold l is positioned in the continuous casting plant and the molten metal is regulated in such a manner that the meniscus 8 of the molten metal poured into said mold is above the horizontal plane 9, passing through the center of curvature of the mold, at a distance which is defined by the relation: 3

4K H R sine I where H is the distance from the meniscus 8 of the molten metal in the mold l to the horizontal plane 9, passing through the center 0 ofits curvature, in cm.

of continuously where R is the radius of curvature of the mold 1, drawn to the point A of intersection of the meniscus 8 with its outer radial working surface, which working surface shapes the external surface ofthe ingot 5, in cm.;

K is the coefficient of crystallization (coefficient of solidification of metal), in cm./min."; and

V is the speed of casting, in cm./min.

The coefficient of crystallization K depends upon the properties of the metal being cast, the temperature thereof, and

1 provides for an unhindered elimination of nonmetallic inclusrons and gas bubbles from the upper portion of the ingot 5,

because they do not contact the growing skin 6, as is evident from FIG. 1.

If the meniscus of the molten metal, however, is disposed above the horizontal plane at a distance considerably greater than the distance as defined by said relation, the nonmetallic inclusions and gas bubbles will be fixed not in the skin on the inner radius of the ingot but in the skin formed on the surface of the mold wall at the outer surface of the ingot.

Hence, the optimum distance from the meniscus to the horizontal plane will be that as defined by the above-said relationship.

An exemplary calculation of the process of casting steel of the grade SL3 (C-0. 15 percent, Si-0.l6 percent, Mn-0.44 percent, S-0.024 percent, P-0.044 percent, Fe-the rest) into the mold l of rectangular cross section is stated below. The speed of casting is equal to V=70 cm./min. The radius of curvature of the mold R=500 cm. Providing these conditions, the coefficient of crystallization amounts to 2.4 to 2.9 cm./min." and the value K=2.6 cm./min." will be adopted for this example.

Substituting the values of these factors into the relationship determines the optimum distance from the meniscus 8 to the horizontal plane 9 passing through the center 0 of curvature of the mold to be 45 cm.

FIG. 2 shows a nomograph, which is plotted according to the foregoing relationship for determining the distance H from the meniscus 8 to the horizontal plane 9 passing through the center 0 of curvature of the mold 1 depending upon the radius of curvature R of the mold 1, speed of casting V and the coefficient of crystallization K. This nomograph is intended for choosing the distance H without having to calculate from the above-mentioned relationship.

Hence, for the example under consideration at the adopted speed of casting, V=70 cm./min. and with the coefficient of crystallization K=2.6 cm./min." the radius R of curvature of the mold can be found from the lower family of curves. It will be seen that it is equal to 500 cm. knowing the radius of curvature of the mold according to the upper family of curves for the same value ofK=2.6 cm./min.' it is possible to determine the distance H equals 45 cm. The sequence of operations in determining the value of H is indicated in FIG. 2 by the arrow B H=R sine What is claimed is:

I. A method of minimizing nonmetallic inclusions and gas bubbles in the outer skin of a continuously cast metal ingot where the molten metal is poured into a curved mold, drawn from the mold and passed through a secondary cooling zone and a roller zone, wherein the improvement comprises maintaining the level of said molten metal in said curved mold at a height H above a horizontal plane passing through the center of curvature of said mold as determined by the relationship:

maintained at a height H of 45 cm. 

1. A method of minimizing nonmetallic inclusions and gas bubbles in the outer skin of a continuously cast metal ingot where the molten metal is poured into a curved mold, drawn from the mold and passed through a secondary cooling zone and a roller zone, wherein the improvement comprises maintaining the level of said molten metal in said curved mold at a height H above a horizontal plane passing through the center of curvature of said mold as determined by the relationship:
 2. A method as claimed in claim 1, wherein V 70 cm./min.; R 500 cm.; K 2.6 cm./min.1/2, H and therefore the molten metal is maintained at a height H of 45 cm. 